It has long been an objective of orthopedic surgeons to find a better method of immobilizing limbs than the use of casts made from plaster. Several schemes based on the use of high polymeric or plastic materials have been devised and several of these are in use. The plastics used are usually applied in a liquid or semi-liquid state and then post-cured to a rigid structure by ultraviolet light, heat, catalysts or other techniques which are well-known in the art of curing of plastic materials.
These methods have found a certain amount of acceptance but they suffer from some drawbacks. The curing reaction is not fast and the equipment which must be used is in many cases cumbersome. These disadvantages are sufficiently serious that plaster is still by far the most usual material used in orthopedic work.
Little attention has been given to the use of thermoplastic high polymers as a cast material. Consideration of the properties of thermoplastics indicates they have one major advantage over the materials heretofore employed. They do not require post-curing. They simply harden on cooling. However, there is no obvious method for applying thermoplastics in orthopedics. Most thermoplastics melt at quite a high temperature and the patient could never tolerate the heat necessary to form the material while directly in contact with or closely adjacent to the skin. Also, there is no simple method for forming a thermoplastic into the shape necessary to conform closely to the configuration required to confine closely the damaged limb or portion of the body to be immobilized.
The thermoplastic cast materials thus far developed suffer from various deficiencies which hinder widespread acceptance. Often the melting point is too high and hardening rate too fast to allow direct forming of the cast on the patient's limb. Melting of the cast material often requires ovens and other cumbersome equipment. Some materials either do not stick to themselves or require careful surface preparation. Some materials do not store well. Often a material which has a low melting point is not sufficiently rigid at temperatures to which the cast will be exposed. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide an orthopedic cast which is clean and simple to apply.
Another object of this invention is the provision of an orthopedic cast which can be applied in a short time.
A further object of the present invention is the provision of an orthopedic cast which is light, strong, and sanitary in use, which allows circulation of air under the cast, and which permits washing of the limb.
It is another object of the instant invention to provide an orthopedic cast which does not require cumbersome equipment to apply.
A still further object of the invention is the provision of an orthopedic cast which reliably adhers to itself during application.
It is a further object of the invention to provide an orthopedic cast which can be applied to the patient while the cast is still in a plastic state.
It is a still further object of the present invention to provide an orthopedic cast which can be pre-formed and which will maintain the pre-formed shape even when rendered plastic.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.